[Federal Register Volume 71, Number 139 (Thursday, July 20, 2006)]
[Rules and Regulations]
[Pages 41121-41125]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-11540]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23706; Directorate Identifier 2006-NE-03-AD; 
Amendment 39-14688; AD 2006-15-08]
RIN 2120-AA64


Airworthiness Directives; Honeywell International Inc. TPE331 
Series Turboprop Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
Honeywell International Inc. TPE331 series turboprop engines with 
certain part numbers of Woodward fuel control unit (FCU) assemblies 
installed. This AD requires initial and repetitive dimensional 
inspections of the fuel control drive, for wear or damage. This AD 
results from reports of loss of the fuel control drive, leading to 
engine overspeed, overtorque, overtemperature, uncontained rotor 
failure, and asymmetric thrust in multi-engine airplanes. We are 
issuing this AD to prevent destructive overspeed that could result in 
uncontained rotor failure, and damage to the airplane.

DATES: This AD becomes effective August 24, 2006.

ADDRESSES: You can get the service information identified in this AD 
from Honeywell Engines, Systems & Services, Technical Data 
Distribution, M/S 2101-201, P.O. Box 52170, Phoenix, AZ 85072-2170; 
telephone: (602) 365-2493 (General Aviation); (602) 365-5535 
(Commercial); fax: (602) 365-5577 (General Aviation and Commercial).
    You may examine the AD docket on the Internet at http://dms.dot.gov 
or in Room PL-401 on the plaza level of the

[[Page 41122]]

Nassif Building, 400 Seventh Street, SW., Washington, DC.

FOR FURTHER INFORMATION CONTACT: Joseph Costa, Aerospace Engineer, Los 
Angeles Aircraft Certification Office, FAA, Transport Airplane 
Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone 
(562) 627-5246; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 
with a proposed airworthiness directive (AD). The proposed AD applies 
to Honeywell International Inc. TPE331 series turboprop engines with 
certain part numbers of Woodward FCU assemblies installed. We published 
the proposed AD in the Federal Register on March 8, 2006 (71 FR 11546). 
That action proposed to require initial and repetitive dimensional 
inspections of the drive splines between the fuel pump and fuel control 
governor, for wear or damage.

Examining the AD Docket

    You may examine the docket that contains the AD, any comments 
received, and any final disposition in person at the Docket Management 
Facility Docket Office between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays. The Docket Office (telephone (800) 
647-5227) is located on the plaza level of the Department of 
Transportation Nassif Building at the street address stated in 
ADDRESSES. Comments will be available in the AD docket shortly after 
the DMS receives them.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Clarification of Discussion Paragraph

    Honeywell International Inc. points out that in the discussion 
section of the Notice of Proposed Rulemaking we stated that 
installation of an improved fuel control will eliminate the overspeed 
condition by better accommodating a drive spline failure. Honeywell 
suggests that we change the discussion to state that replacing an 
affected fuel control assembly with an improved fuel control assembly 
will only reduce the possibility of an overspeed, rather than eliminate 
it altogether. We agree that Honeywell's suggestion has some logic from 
a risk management perspective. We recognize that the improved fuel 
control may not eliminate the possibility of a drive spline failure or 
the resulting engine overspeed condition, but we intend that it will 
eliminate a destructive overspeed due to this spline failure. We have, 
however, changed paragraph (d) of the final rule (the statement of the 
unsafe condition) to clarify that we expect that the AD will prevent 
destructive overspeed that could result in uncontained rotor failure, 
and damage to the airplane.

Suggestion to Specifically Reference Pump Splines

    Honeywell International Inc. also suggests that we add the words 
``or pump'' after ``fuel control'' in both paragraphs (f)(2) and (g)(2) 
of the proposed rule. Honeywell points out that the proposed 
inspections also include the fuel pump spline as well as the fuel 
control splines. We agree that the required inspections include the 
fuel pump spline and that if the fuel pump spline fails inspection, the 
fuel pump would require repair or replacement. Therefore, we have added 
references to the fuel pump in paragraphs (f), (g), and (l) of the 
final rule. We have also split the repair and replace requirement in 
paragraphs (f) and (g) into one sub-paragraph for the fuel pump, (f)(2) 
and (g)(2), and one for the fuel control assembly, (f)(3) and (g)(3), 
which we now refer to as the fuel control unit (FCU) assembly. We made 
these changes to keep clear that the replacement requirements of the AD 
call for ``modified'' FCU assemblies for multi-engine airplanes. Fuel 
pump assemblies whose splines fail dimensional inspection may be 
replaced with serviceable fuel pump assemblies.

Request To Add the Word ``Governor''

    Honeywell International Inc. also requests that we add the word 
``governor'' to describe the splined driveshafts between the fuel pump 
and the FCU. Honeywell points out that the proposal could be read so as 
not to include a required inspection of the quill shaft internal to the 
fuel control. We agree, and have added a definition of the term ``fuel 
control drive'' to paragraph (k) of the final rule that includes the 
change of ``fuel control'' to ``fuel control governor.''

Claim That Destructive Overspeed Is Still Possible

    An FAA-approved repair station, Turbine Standard, Ltd, claims that 
destructive engine overspeed is really only possible on the ground with 
the prop ``on the start locks'' and will continue to be possible with 
the new modified fuel control assembly. The commenter states that 
according to Honeywell's Operating Information Letters OI331-12R4, 
dated March 29, 2006, and OI331-18R2, dated March 29, 2006, the 
possibility of uncontained separation of the engine's high speed 
rotating components still exists, at certain conditions. Furthermore, 
the commenter appears to question the need for this AD by pointing out 
that wear of the FCU and fuel pump drive can be adequately managed by 
following the recommended maintenance program for the engine and that 
any FCUs that showed heavy spline wear were addressed by a previous AD, 
AD 94-26-07.
    We do not agree. The proposed rule and this AD address a continuing 
problem that has caused 51 known incidents over the past 30 years. We 
believe that the fuel pump and fuel control spline failures represent a 
serious unsafe condition that requires mandatory inspections and 
replacement of existing fuel control designs to warrant AD action 
rather than reliance on recommended maintenance practices. Even after 
issuing AD 94-26-07, we continue to receive reports of fuel control 
drive failures, overspeed, and destructive overspeed events. With a 
modified FCU installed, AD 94-26-07 will no longer apply.
    Whether destructive overspeeds will continue to be possible with 
the new modified fuel control assembly, we recognize that this failure 
condition is rare and only exists under certain high-temperature and 
high-altitude ground start conditions, with certain older design 
engines while the prop is ``on the locks''. When this set of rare 
conditions is coupled with the fuel control drive low failure rate, a 
destructive overspeed is improbable. We consider the modified FCU 
assembly to be safe.

Claim That Asymmetric Thrust Would be More Prevalent

    Turbine Standard, Ltd also claims that the modified fuel control 
assembly installed on an engine on a multi-engine airplane would 
actually make asymmetric thrust more likely in the event of a fuel pump 
or fuel control drive spline failure. The commenter explains that after 
the failure of a fuel control drive on a modified fuel control 
assembly, the modified fuel control would deliver only 180 PPH of fuel 
flow, which is below flight idle fuel flow. Since fuel flows for take 
off thrust are normally very high and the failure mode of an unmodified 
fuel control unit typically delivers more fuel flow, the commenter 
concludes that the aircrew would be in a worse situation with a 
modified fuel control after suffering drive spline failure than with a 
non-modified fuel control.
    We do not agree. While it is true that the fuel flow after drive 
spline failure

[[Page 41123]]

with a modified fuel control unit may result in a more pronounced 
asymmetric thrust condition at takeoff, we believe that after 
considering all ground and flight conditions, the modified FCU assembly 
is much safer than the applicable FCU assembly on the multi-engine 
aircraft. In addition, with a modified fuel control, the failure mode 
would produce a clearly evident decrease in thrust that a trained 
aircrew can easily recognize and safely handle, even on takeoff.

AD Does Not Address Recommendations to the Pilot on Negative Torque 
Sensing

    Turbine Standard, Ltd also claims that the proposed AD does not 
address recommendations to the pilot if the engine starts to experience 
``negative torque sensing'' during flight. The commenter reasons that 
after the failure of a fuel control drive spline, the modified fuel 
control assembly will deliver 180 PPH of fuel flow, which may be below 
flight idle fuel flow, and the engine may experience negative torque 
sensing (NTS). In addition, ``negative torque sensing'' at higher than 
normal engine speeds for long periods, might damage the propeller.
    We do not agree that the AD needs to include mandatory instructions 
to the aircrew concerning NTS. The commenter is correct that during 
flight with the modified FCU assembly installed, the engine may 
experience NTS after failure of a fuel control drive. We believe that 
having the pilot shut down the engine as soon as possible after drive 
spline failure by recognizing an unresponsive power lever, consistent 
with the safe operation of the airplane, is the best action. We have 
changed paragraph (o) of the final rule to reference Honeywell's 
operating information letters.

Claim That the Modified FCU Assembly Is Not Necessary

    Lastly, Turbine Standard, Ltd claims that the modified FCU assembly 
is not necessary because of the propeller governor response to an 
engine overspeed, if the airplane is equipped with torque and 
temperature limiting (TTL) devices. The commenter believes that fuel 
bypassing the TTL devices and the propeller governor should maintain 
engine speed at its set point after a fuel control drive failure.
    We do not agree. Engine testing shows that the TTL devices cannot 
bypass sufficient fuel and the propeller governor cannot maintain speed 
consistently enough to ensure a safe operation of the TPE331 engine. In 
addition, since the TTL devices are optional devices for some aircraft, 
the TTL's marginal and temporary benefit is not a safe alternative.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    We estimate this AD will affect 3,250 engines installed on 
airplanes of U.S. registry. We also estimate it will take about one 
work-hour per engine to replace the FCU assembly during a normal 
scheduled overhaul. We also estimate it will take about three work-
hours to perform a dimensional inspection of the fuel control drive. 
The average labor rate is $65 per work-hour. A replacement FCU assembly 
will cost about $9,700 per engine. We estimate that on each engine, one 
FCU assembly inspection will be performed, and each engine will have 
the FCU assembly replaced. Based on these figures, we estimate the 
total cost of the AD to U.S. operators to be $32,370,000.
    The Agency is committed to updating the aviation community of 
expected costs associated with the MU-2B series airplane safety 
evaluation conducted in 2005. As a result of that commitment, the 
accumulating expected costs of all ADs related to the MU-2B series 
airplane safety evaluation may be found at the following Web site: 
http://www.faa.gov/aircraft/air_cert/design_approvals/small_airplanes/cos/mu2_foia_reading_library/.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and
    (3) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a summary of the costs to comply with this AD and 
placed it in the AD Docket. You may get a copy of this summary at the 
address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the Federal Aviation Administration amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2006-15-08 Honeywell International Inc. (formerly AlliedSignal Inc., 
Garrett Engine Division; Garrett Turbine Engine Company; and 
AiResearch Manufacturing Company of Arizona): Amendment 39-14688; 
Docket No. FAA-2006-23706; Directorate Identifier 2006-NE-03-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective August 
24, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Honeywell International Inc. TPE331-1, -
2, -2UA, -3U,

[[Page 41124]]

-3UW, -5, -5A, -5AB, -5B, -6, -6A, -10, -10AV, -10GP, -10GT, -10P, -
10R, -10T, -10U, -10UA, -10UF, -10UG, -10UGR, -10UR, -11U, -12JR, -
12UA, -12UAR, and -12UHR turboprop engines with the part numbers (P/
Ns) of Woodward fuel control unit (FCU) assemblies listed in this 
AD, installed. These engines are installed on, but not limited to, 
the following airplanes:

------------------------------------------------------------------------
              Manufacturer                            Model
------------------------------------------------------------------------
AERO PLANES, LLC (formerly McKinnon      G-21G.
 Enterprises).
ALLIED AG CAT PRODUCTIONS (formerly      G-164 Series.
 Schweizer).
AYRES..................................  S-2R Series.
BRITISH AEROSPACE LTD (formerly          3101 and 3201 Series, and
 Jetstream).                              HP.137 JETSTREAM MK.1.
CONSTRUCCIONES AERONAUTICAS, S.A.        C-212 Series.
 (CASA).
DEHAVILLAND............................  DH104 Series 7AXC (DOVE).
DORNIER................................  228 Series.
FAIRCHILD..............................  SA226 and SA227 Series
                                          (SWEARINGEN MERLIN and METRO
                                          SERIES).
GRUMMAN AMERICAN.......................  G-164 Series.
MITSUBISHI.............................  MU-2B Series (MU-2 Series).
PILATUS................................  PC-6 Series (FAIRCHILD PORTER
                                          and PEACEMAKER).
POLSKIE ZAKLADY LOTNICZE SPOLKA          PZL M18, PZL M18A, PZL M18B.
 (formerly Wytwornia Sprzetu
 Komunikacyjnego).
PROP-JETS, INC.........................  400.
RAYTHEON AIRCRAFT (formerly Beech).....  C45G, TC-45G, C-45H, TC-45H, TC-
                                          45J, G18S, E18S-9700, D18S,
                                          D18C, H18, RC-45J, JRB-6, UC-
                                          45J, 3N, 3NM, 3TM, B100, C90
                                          and E90.
SHORTS BROTHERS and HARLAND, LTD.......  SC7 (SKYVAN) Series.
THRUSH (ROCKWELL COMMANDER)............  S-2R.
TWIN COMMANDER (JETPROP COMMANDER).....  680, 690 and 695 Series.
------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from reports of loss of the fuel control 
drive, leading to engine overspeed, overtorque, overtemperature, 
uncontained rotor failure, and asymmetric thrust in multi-engine 
airplanes. We are issuing this AD to prevent destructive overspeed 
that could result in uncontained rotor failure, and damage to the 
airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.

Initial Inspection of Engines With Affected FCU Assemblies

    (f) At the next scheduled inspection of the fuel control drive, 
but within 1,000 hours-in-service after the effective date of this 
AD:
    (1) Perform an initial dimensional inspection of the fuel 
control drive for wear or damage. Information on spline inspection 
can be found in Section 72-00-00 of the applicable maintenance 
manuals.
    (2) Repair or replace the fuel pump, if the spline fails the 
dimensional inspection, with any serviceable fuel pump.
    (3) Repair or replace the FCU assembly, if the splines fail the 
dimensional inspection, with a serviceable modified FCU assembly.

Repetitive Inspections of Engines With Affected FCU Assemblies

    (g) Thereafter, within 1,000 hours since-last-inspection:
    (1) Perform repetitive dimensional inspections of the fuel 
control drive, for wear or damage. Information on spline inspection 
can be found in Section 72-00-00 of the applicable maintenance 
manuals.
    (2) Repair or replace the fuel pump, if the spline fails the 
dimensional inspection, with any serviceable fuel pump.
    (3) Repair or replace the FCU assembly if the splines fail the 
dimensional inspection, with a serviceable modified FCU assembly.

TPE331-1, -2, and -2UA Series Engines

    (h) For TPE331-1, -2, and -2UA series engines, replace Woodward 
FCU assemblies, P/Ns 869199-13/ -20/ -21/ -22/ -23/ -24/-25/ -26/ -
27/ -28/ -29/ -31/ -32/ -33/ -34, and -35, with a serviceable, 
modified FCU assembly the next time the FCU assembly is removed for 
cause that requires return, or when the FCU assembly requires 
overhaul, but not later than December 31, 2012. Information on 
replacement FCU assembly P/Ns, configuration management, rework, and 
replacement information, can be found in Honeywell Alert Service 
Bulletin (ASB) No. TPE331-A73-0271, Revision 1, dated January 25, 
2006.

TPE331-3U, -3UW, -5, -5A, -5AB, -5B, -6, -6A, -10AV, -10GP, -10GT, -
10P, and -10T Series Engines

    (i) For TPE331-3U, -3UW, -5, -5A, -5AB, -5B, -6, -6A, -10AV, -
10GP, -10GT, -10P, and -10T series engines, replace Woodward FCU 
assemblies, P/Ns 893561-7/ -8/ -9/ -10/ -11/ -14/ -15/ -16/ -20/ -
26/ -27, and -29, and P/Ns 897770-1/ -3/ -7/ -9/ -10/ -11/ -12/ -14 
/ -15/ -16/ -25/ -26, and -28, with a serviceable, modified FCU 
assembly the next time the FCU assembly is removed for cause that 
requires return, or when the FCU assembly requires overhaul, but not 
later than December 31, 2012. Information on replacement FCU 
assembly P/Ns, configuration management, rework, and replacement 
information, can be found in Honeywell ASB No. TPE331-A73-0262, 
Revision 2, dated June 17, 2005.

TPE331-10, -10R, -10U, -10UA, -10UF, -10UG, -10UGR, -10UR, -11U, -12JR, 
-12UA, -12UAR, and -12UHR Series Engines

    (j) For TPE331-10, -10R, -10U, -10UA, -10UF, -10UG, -10UGR, -
10UR, -11U, -12JR, -12UA, -12UAR, and -12UHR series engines, replace 
Woodward FCU assemblies, P/Ns 897375-2/ -3/ -4/ -5/ -8/ -9/ -10/ -
11/ -12/ -13/ -14/ -15/ -16/ -17/ -19/ -21/ -24/ -25/ -26, and -27, 
and P/Ns 897780-1/ -2/ -3/ -4/ -5/ -6/ -7/ -8/ -9/ -10/ -11/ -14/ -
15/ -16/ -17/ -18/ -19/ -20/ -21/ -22/ -23/ -24/ -25/ -26/ -27/ -30/ 
-32/ -34/ -36/ -37, and -38, and P/Ns 893561-17/ -18, and -19, with 
a serviceable, modified FCU assembly the next time the FCU assembly 
is removed for cause that requires return, or when the FCU assembly 
requires overhaul, but not later than December 31, 2012. Information 
on replacement FCU assembly P/Ns, configuration management, rework, 
and replacement information, can be found in Honeywell ASB No. 
TPE331-A73-0254, Revision 2, dated June 17, 2005.

Definitions

    (k) For the purposes of this AD:
    (1) A ``serviceable, modified FCU assembly'' for engines 
affected by paragraph (h), (i), or (j) of this AD, is an FCU 
assembly with a P/N not listed in this AD.
    (2) The ``fuel control drive'' is a series of mating splines 
located between the fuel pump and fuel control governor, consisting 
of the following four drive splines: The fuel pump internal spline, 
the fuel control external ``quill shaft'' spline, and the stub shaft 
internal and external splines.
    (3) A ``removal for cause that requires return'', for engines 
affected by paragraph (h), (i), or (j) of this AD, is an FCU 
assembly that has displayed an unserviceable or unacceptable 
operating condition requiring the FCU to be removed from service and 
sent to a repair or overhaul shop.

[[Page 41125]]

Optional Method of Compliance for TPE331 Series Engines Installed On 
Single-Engine Airplanes

    (l) As an optional method of compliance to paragraph (h), (i), 
or (j) of this AD, for TPE331 series engines installed on single-
engine airplanes, having an affected Woodward FCU assembly perform 
the following steps as necessary:
    (1) Continue repetitive dimensional inspections of the fuel 
control drive, for wear or damage as specified in paragraph (g)(1) 
of this AD.
    (2) Repair or replace the fuel pump or FCU assembly if the 
splines fail the dimensional inspection, with any serviceable fuel 
pump or FCU assembly.

Terminating Action

    (m) Performing an FCU assembly replacement as specified in 
paragraph (h), (i), or (j) of this AD, is terminating action for the 
initial and repetitive inspections required by this AD.

Alternative Methods of Compliance

    (n) The Manager, Los Angeles Aircraft Certification Office, has 
the authority to approve alternative methods of compliance for this 
AD if requested using the procedures found in 14 CFR 39.19.

Related Information

    (o) Information pertaining to operating recommendations for 
applicable engines after a fuel control drive failure is contained 
in OI 331-12R5 dated July 10, 2006, for multi-engine airplanes and 
in OI 331-18R3 dated July10, 2006, for single-engine airplanes.

    Issued in Burlington, Massachusetts, on July 14, 2006.
Francis A. Favara,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-11540 Filed 7-19-06; 8:45 am]
BILLING CODE 4910-13-P